One Year War is a third-person action shooting game based on the original Mobile Suit Gundam television series from 1979. Following the events of the "One Year War", the player takes the role of young pilot Amuro Ray through 28 missions that recreate key events from the original series. The game includes both ground and space battle stages, and there are a wide variety of different weapons and machines to use. One notable feature is the so-called "Memorial Actions" system, where completing special requirements that match events in the series will unlock additional bonus content.